BUGFIX: Fix release script.

BUGFIX: Do not require yarn to be present when installing the package…

… since it is a devDependency engine

BUGFIX: Revert the switch to the internal flow gen-flow-files command…

… to reduce the number of dependencies

This reverts commit da19335.

BUGFIX: Switch to the internal flow gen-flow-files command to reduce …

…the number of dependencies

FEATURE: Integrate semantic-release